We are requesting funds to purchase a Seahorse XFe24 Analyzer to replace a similar instrument that is more than 10 years old. In addition, the manufacturer Agilent Technologies has upgraded the model we are currently using and will no longer support the older instruments after 2018. The Seahorse XFe24 Analyzer has become a staple of laboratories doing mitochondrial biology. It uses solid-state disposable optical sensors to simultaneously measure mitochondrial respiration (oxidative phosphorylation) via the oxygen consumption rate, and glycolysis via the extracellular acidification rate in cell cultures, tissues and isolated mitochondria, allowing investigators to profile cellular metabolic function. Methods are also available for quantifying endogenous and exogenous fatty acid oxidation, substrate oxidation, and metabolic phenotype. The Agilent Seahorse XF technology has been used with a variety of cell lines, including primary cells, adherent and suspension cell lines, isolated mitochondria, islets, 3D spheroids, Zebrafish embryos, C. elegans, D. melanogaster, yeast, and other biological materials. Importantly, this is a non-invasive methodology and cells can be used post-measurement for other applications or chronic (long-term) experiments. A key advantage of the Seahorse XFe24 is that it allows measurement of mitochondrial function in intact cells or tissue samples avoiding the requirement for isolation of mitochondria and potential artifacts that can occur during tissue disruption and organelle fractionation. Dr. Van Remmen has extensive experience with this instrument and currently assists other investigators at the VA and the OMRF and OUHSC campuses in data collection using the Seahorse Analyzer through her role as Leader of the Integrative Redox Biology Core of the Oklahoma Nathan Shock Center. The charges from users of the Shock Center Core can be used to support service contract and maintenance costs. The Seahorse XFe24 will be a valuable tool for our VA investigators. It will be utilized by eight VA investigators: five with funded VA Merit grants and three potential users who have VA Merit grants pending.